This invention relates to an electronic circuit device made by packing a module structure comprising a multi-layer circuit board which connects a semiconductor operating element, semiconductor memory elements, and passive elements thereon into a single package with a packing resin component.
Modules using semiconductor integrated circuits have been used not only for small electronic devices such as video cameras and cellular phones but also to control car engines and revolutions of train wheels. Each of such modules builds electronic parts having semiconductor functions and electronic parts having resistance functions on a circuit board to control signals. To increase the reliability, an example of such modules is manufactured by bonding a circuit board in a casing, mounting electronic parts in place on the circuit board and packing thereof with silicone gel which is flexible in a wide temperature range. This example has been well known as a module that can improve the withstand voltage characteristic. However, this kind of module uses a casing. This results in making its size greater. Further, silicone gel takes a lot of time in injection and hardening and is low in heat radiation characteristic. Japanese Application Patent Laid-Open Publication No. Hei 10-79453 discloses a method of packing a module with a thermosetting resin component. This method packs one side of a circuit board with a thermosetting resin. As the coefficient of thermal expansion of the thermosetting resin component is different from that of the circuit board, the module is apt to warp. Japanese Application Patent Laid-Open Publication No. Hei 10-135377 discloses a method to make the coefficient of thermal expansion of the thermosetting resin closer to that of the circuit board. However, as this method also packs only one side of the circuit board, the interface between the circuit board and the thermosetting resin component is mostly exposed to the atmosphere and apt to be separated.
As a method for molding the whole circuit board, Japanese Application Patent Laid-Open Publication No. Hei 09-51056 discloses a method to pack the ceramic multi-layer circuit board with a packing material. This invention is characterized in that the electrode connection section is stepped along the layers of the multi-layer circuit board, but this invention has no means to improve the capability of heat radiation of the module.
Japanese Application Patent Laid-Open Publication No. Hei 08-78618 discloses a method to improve the capability of heat radiation of the module by using a thermal conductive block. This thermal conductive block for heat radiation is made of aluminum nitride having a high modulus of elasticity. So when exposed to a rapid temperature change such as from −55° C. to 150° C., the packing resin component may have cracks due to thermal stresses.
Japanese Application Patent Laid-Open Publication No. 2001-291808 discloses a power semiconductor integrated circuit which eliminates separation and cracks in the module by bonding a base material and a heat sink together with an adhesive which is made by dispersing ceramics in a brazing material made of aluminum alloy and copper alloy to have a thermal expansion coefficient which is between those of the base material and the heat sink. However, this integrated circuit is not a module structure which connects a semiconductor operating element, semiconductor memory elements, and passive elements thereon and cannot be used as an electronic circuit device.
Japanese Application Patent Laid-Open Publication No. Hei 06-196614 discloses an invention concerning a lead frame made by bonding a stress relief material whose thermal expansion coefficient is close to that of a semiconductor device to the lead frame. This lead frame is resistant to cracks due to stresses but this invention does not take the heat radiation of the stress relief material into consideration. Further, as this invention tries to make the thermal expansion coefficient of the stress relief material close to that of a semiconductor device, a thermal stress will converge on the interface between the lead frame and the stress relief material, and consequently, the lead frame may separate from the stress relief material.
Japanese Application Patent Laid-Open Publication No. 2001-196513 discloses an invention concerning a compound metallic material of high thermal conductivity and low thermal expansion which is made from copper and copper oxide. However, this is not related to a resin packed electronic circuit device which connects a semiconductor operating element, semiconductor memory elements, and passive elements thereon.
Further, Japanese Application Patent Laid-Open Publication No. 2000-119629 discloses an invention concerning an adhesive resin component mixed up with inorganic filling material that contains 50 to 99.9 parts by weight of silver and 0.1 to 50 parts by weight of copper oxide. This adhesive resin component is used to bond a lead frame to a semiconductor chip. However, this invention does not take the capability of heat radiation and resistance to thermal stresses into consideration.                [Patent Document 1]        Japanese Application Patent Laid-Open Publication No. Hei 10-79453        [Patent Document 2]        Japanese Application Patent Laid-Open Publication No. Hei 10-135377        [Patent Document 3]        Japanese Application Patent Laid-Open Publication No. Hei 09-51056        [Patent Document 4]        Japanese Application Patent Laid-Open Publication No. Hei 08-78618        [Patent Document 5]        Japanese Application Patent Laid-Open Publication No. 2001-291808        [Patent Document 6]        Japanese Application Patent Laid-Open Publication No. Hei 06-196614        [Patent Document 7]        Japanese Application Patent Laid-Open Publication No. 2001-196513        [Patent Document 8]        Japanese Application Patent Laid-Open Publication No. 2000-119629        